Wireless networking has become increasingly popular in a wide range of home electronic devices. Wireless connections such as IEEE 802.11ac® generally have enough bandwidth and robustness to pass video signals, such as between a home gateway and a set top box. Televisions also commonly have wireless interfaces to receive video content and other content. Wireless receiver sensitivity is an important product parameter, so a device supporting wireless networking may have one or more antennas incorporated into its enclosure. Also, the receiver circuitry itself may be sensitive to noise received through power or ground connections. Examples of wireless networking technologies include IEEE 802.11 (also known as Wi-Fi), Bluetooth, and Zigbee among many others. The most popular wireless interface devices operate within the Industrial, Scientific and Medical (ISM) frequency bands and the Unlicensed National Information Infrastructure (UNII) bands. The ISM bands typically used in the United States are 2.4 to 2.5 GHz and 5.725 to 5.875 GHz. The UNII bands expand the 5 GHz ISM band to 5.15 GHZ to 5.925 GHz. These frequencies are exemplary; frequency allocations are changed by the FCC periodically and new allocations, such as the Citizens Broadband Radio Service (CBRS), are often added.
In addition to the wireless interfaces used on modern consumer electronics, high speed digital wired interfaces are also common. An example high speed digital wired interface is High Definition Multimedia Interface® (HDMI), a very common and popular home networking wired interface for video delivery. An HDMI interface typically connects a set top box or other video source to a display device such as a television or video projector. An HDMI transmit interface is sourced from an integrated circuit providing an assortment of signal and clock traces to an external connector. The external HDMI connector receives the signals from the integrated circuit and deploys them in a standardized connector assembly. HDMI also specifies a receive interface on devices such as video displays or televisions. In an HDMI receive configuration, the external HDMI connector assembly receives signals and deploys the signal and clock leads onto traces on the motherboard. Those HDMI traces run to an integrated circuit that receives and processes them. Generally, though the descriptions use the example embodiment of an HDMI source device, the invention is equally applicable to an HDMI sink device. When an HDMI source device is first connected to an HDMI sink device, they exchange configuration parameters, if needed.
The frequencies of signals, including clock signals, on many wired interfaces overlap with the frequencies used by wireless interfaces. For example, while the frequency content of HDMI signals does vary depending upon the specific settings of an HDMI interface, such as resolution and frame rate, HDMI signals consistently have frequency content that overlaps with that of typical wireless interfaces. When both technologies are deployed in a single device, energy from HDMI signals may be radiated as the HDMI traces run between the integrated circuit and the HDMI connector.
Additionally, some HDMI cables have low levels of shielding, also allowing HDMI signals to radiate from the cable outside of the HDMI connector on the STB. If this radiated energy is absorbed by wireless antennas or circuitry, then that energy contributes noise to the wireless receiver, resulting in decreased wireless range and throughput. This decreased performance is detrimental to the usefulness of the product. Consumer electronic devices, such as set top boxes are under pressure to be as small and compact as possible. Display devices are under similar pressure to be thin and minimize externally visible connections. This decrease in size often forces the wired interfaces and the wireless interfaces closer together, which tends to increase radiative coupling between wired interface internal traces and external wiring with the wireless receiver assembly.
While HDMI has been discussed as an exemplary high speed digital wired interface, many other similar technologies exist. Some other examples are Multimedia over Coax Alliance (MoCA), Ethernet, and Universal Serial Bus (USB).
Therefore, a need exists for improved methods and systems to reduce wired interface interference with wireless interfaces in electronic devices.